The popularity of denim fabrics among consumers of all ages has been well documented by sales in a large number of countries throughout the world. A major proportion of the denim garments sold are treated to impart some aesthetic or fashionable character to the fabric or garment. Two principle means of imparting an aesthetically pleasing decolorized look or fashionably faded look to denim fabrics or garments are the processes of stonewashing or, alternatively, ice washing. Stonewashing is a physical process which creates a "used and abused" appearance in fabric through a physical washing in the presence of stones or rocks having an abrasive surface.
Alternatively, fabrics may also be decolorized by ice washing. Generally, "ice washing" involves the use of a bleach such as sodium hypochlorite or potassium permanganate which is loaded onto an inert particle such as a porous rock or pumice stone. The potassium permanganate soaked stones are loaded into an industrial washing machine with the fabric. Once the machine is activated, the bleach-laden stones then contact the denim resulting in a discoloration of the exterior surface of the fabric.
A number of problems are presented by stonewashing and ice washing processes. First the use of pumice stones can generally create a considerable amount of damage to the goods as well as to the machinery used in the process. Specifically, the coarse or rough nature of the stones used in these prior art processes often result in wearing or destruction which is difficult to control. This wearing may result in unintended damage to the processing machinery necessitating repair or to the fabric making the garments unmarketable.
Moreover, the use of pumice stones creates problems in cleaning the fabric and the machinery once the processing has ended. Specifically, each denim garment must be manually "derocked" to remove the stones that have found their way into pockets, creases, and interior folds in the garment. This manual "derocking" of garments is completed at great expense which is ultimately reflected in the price the consumer must pay for the garment. Additionally, the industrial washing machines must be manually derocked by any number of workers who must literally shovel out the washing machines.
Furthermore, potassium permanganate, commonly used in ice washing processes, results in a manganese dioxide (MnO.sub.2) chemical by-product after bleaching which has a brown sedimentary character. This sediment may be difficult to remove from the machines as well as from the fabric or garments. These inherent limitations in the prior art make these processes generally unsuitable for efficient large-scale production of decolorized denim. Given the limitations of the prior art there is substantial need for an improved process and composition for creating an aesthetic or fashionable decolorized look in denim fabric and garments.